Explosive warhead



Aug. 25, 1964 M. A. COOK ETAL EXPLOSIVE WARHEAD Filed Aug. 14, 1959 2 Sheets-Sheet 1 INVENTORS MELVIN A. COOK WAYNE O. URSENBACH BY z ATTORNEYS.

State as 3,145,656 Patented Aug. 25, 1964 3,145,656 EXPLQSIVE WARHEAD M'eivin A. Cook and Wayne t Ursenhach, Salt Lake City, Utah, assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Aug. 14, 1959, Ser. No. 833,652 7 Claims. (Cl. 1132-24) This invention relates to detonation initiators for explosive warheads and more particularly to such devices for use with multiple shaped charge, rod, fragmentation and other types of warheads in which optimum performance depends upon the detonation front having a particular geometric configuration.

The successful use of warheads of the type referred to depends largely upon the geometrical configuration of the impinging detonation front. A multiple shaped charge warhead, for example, has a metal liner having a multiplicity of conical portions which collapse and form radially outwardly projecting jets of metal when the warhead is detonated. The proper formation of such jets depends upon the substantially simultaneous initiation of the warhead explosive at all points along the cylindrical surface of a central bore extending between the ends of the warhead. The initiators heretofore available have generated spherically expanding detonation fronts which cannot effeet a simultaneous detonation along a cylindrical surface.

It is an object of the present invention to provide a device to improve the performance of warheads of the type referred to by generating a detonation front having an opitmum geometrical configuration.

It is a further object to provide a device for detonating a warhead having a cylindrical bore in a manner whereby detonation is eflected simultaneously at all points between the ends of the bore.

' Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a longitudinal section of a multiple shaped charge warhead employing the present invention;

FIG. 2 is a section taken along line 22 of FIG. 1;

FIG. 3 is a side elevation of a guided missile in which the device of FIG. 1 is used;

FIGS. 4A, 4B and 4C are diagrams illustrating sequential conditions following the end detonation of an initiator which is loaded into a thin walled sleeve having uniform wall thickness;

FIGS. 5A, 5B and 5C are sections like FIG. 1, but shortened for illustrative purposes, and illustrating generally corresponding sequential conditions of the device of FIG. 1;

FIG. 6 is a longitudinal section of an alternative form of the present invention; and

FIG. 7 is a section taken along line 7-7 of FIG. 6.

Referring to the drawing and in particular to FIG. 1, a multiple shaped charge warhead It consists of a generally cylindrical explosive charge 12 with a metal liner 14 thereabout, the liner being in the form of a multiplicity of conical portions 16 so constructed that when charge 12 is detonated each conical portion collapses and forms a jet of molten metal 18, shown in phanton lines, such warhead being commonly employed in an anti-aircraft missile 19, FIG. 3, and being old in the art. Explosive charge 12 has a cylindrical bore 2i; extending between the ends thereof and is detonated by an axial initiator Z2 comprising a cylindrical initiator explosive charge 24 loaded into a tapered sleeve 25 made of an inert material, such as mild steel, having the characteristic of delaying the propagation of a detonation front in proportion to its thickness along the path of the detonation front, as will hereinafter be further described. The sleeve has a thick end 28 decreasing in wall thickness along its length to a thin end 3%) and is adapted for end detonation at thick end 28 by means of electric detonator 32. Tapered sleeve 26 is axially disposed within bore 20 between opposite ends thereof and held in a spaced relationship thereto by means of spacers 34, 36, providing an annular space 38 between tapered sleeve 26 and explosive charge 12, the annular space being important to the present invention for reasons which will be hereinafter apparent.

When a cylindrical charge of explosive 40, FIGS. 4A, 4B, 4C, similar to initiator charge 24 except that it is loaded into a thin walled sleeve 42 having a uniform wall thickness is end detonated, the charge does not detonate simultaneously along its length, there being instead a spherically expanding detonation front, to be hereinafter referred to as the end on detonation front, which starts at point A, the point of detonation, and which propagates end on within the charge along its length so that at sequential intervals after detonation such detonation front might be expected to assume the forms of broken lines 44a, 44b, 440, which represent spherical surfaces expanding in the directions of the arrows X. There is also a lateral detonation front starting near the intersection of the end on detonation front and the cylindrical boundary of the charge which propagates laterally outward in the form of a generally spherical expanding surface. Such lateral front does not appear in FIG. 4A since the end on detonation front has not intersected the boundaries of the charge, but at the time interval represened by FIGS. 43 and 4C, such front might be expected to assume the form of broken lines dob and 460 respectively, which represent generally spherical surfaces expanding in the direction of arrows X. FIG. 40 further illustrates the effect of charge 40 when employed as an axial initiator in a warhead charge 43 like warhead charge 12. Instead of effecting simultaneous initiation along the bore the generally spherical lateral front causes non-simultaneous detonation whereby the end of warhead charge 48 nearest to point A is detonated first causing the asymmetrical collapse of the conical portions 54) of the liner and providing undesired asymmetrically formed jets of metal 52, as shown.

It is apparent, from the foregoing explanation that a sleeve about an end detonation initiator charge is in the path of propagation of the lateral detonation front. It has been observed that if such sleeves are made of certain non-explosive inert materials such as steel, glass or brass the propagation of the lateral front is delayed and the magnitude of delay is nearly proportional to the sleeve wall thickness. In fact, magnitudes of delay may be attained which are in the order of the time it takes for the end on detonation front to travel substantial distances along the length of the charge. For example, a mild steel sleeve having a wall thickness of the order of 0.5 inch about a cylindrical charge of cast pentolite 8.0 inches long and 0.625 inch in diameter can delay the propagation of the lateral front by a time interval of the order of 40 micro secs which is approximately the same interval of time it takes for the end on detonation front to travel from one end of the charge to the other. In the present invention the values for the taper in wall thickness of tapered sleeve 26 are chosen to create a propagation delay gradient along the length of charge 24 such that the lateral front, which would otherwise assume the form of an expanding generally spherical surface is caused to assume the form of an expanding cylindrical surface at the instant it impinges upon the surface of bore 2%. The end on detonation front propagates as in the aforesaid case of the initiator charge loaded into a thin walled sleeve and might be expected to assurnethe form of broken lines 54a, 54b, 54c,

3,1a5,ese

3 FIGS. 5A, 5B, 5C, expanding in the directions of arrows Y at sequential intervals after charge 24 is detonated at point B. The lateral detonation front does not appear in FIG. 5A since the end on detonation front has not intersected the boundaries of the charge. Nor does it appear in FIG. 513 having been delayed by the delay gradient produced by sleeve 26. However, as shown in FIG. 5B sleeve 26 expands and breaks up in the region generally behind broken line 5412, the advancing end on detonation front, causing etiects including a shock wave and products of sleeve expansion and break up which propagate radially outward in the annular zone 56 about the portion of the sleeve which has expanded and broken. up. These effects are undesirable in that they precede the detonation wave and will physically damage an explosive in their path, and in the case of a typical brittle warhead explosive will break it up before the detonation front reaches it causing failure of detonation. Such undesirable effects are, however, confined within a certain radial distance beyond the sleeve. The purpose of annular space 33 is to provide a buffer zone about tapered sleeve 26 to permit such outwardly propagating effects to expand within such radial distance or space without damaging the warhead charge. Finally, at the time interval after detonation represented by FIG. 5C, the lateral detonation front assumes the form of broken line 58, a generally cylindrical surface expanding in the direction of the impinge arrows Y, effecting substantially simultaneous initiation at all points along bore 20, thereby simultaneously and symmetrically collapsing the conical portions 16 of the liner along the length of the warhead forming metal jets 18.

FIGS. 6 and 7 illustrate a multiple shaped charge Warhead as embodying several variations in the basic principles of the invention, such warhead being similar to the device heretofore described except as will be mentioned. A cylindrical initiator explosive charge 62 is loaded into an inner sleeve 64 made of an inert material having the same characteristics as the material employed in the sleeve of the device heretofore described. However, inner sleeve 64 has a double taper with maximum wall thickness at the midpoint between its ends and minimum wall thickness at its ends, the initiator charge being adapted for detonation at the midpoint by means of electricdetonator 66 so that the sleeve wall thickness decreases in either of the opposite directions away from the point of detonation along its length. It is apparent that such arrangement is the equivalent of placing'two end detonated single taper sleeves end to end, with the resultant effect that the device is capable of effecting simultaneous detonation for a warhead of twice the length that can be detonated with a single taper sleeve. An outer sleeve 63 is disposed concentrically about inner sleeve i with an annular space '70 therebetween providing a buffer zone to prevent damage to the outer sleeve by the outwardly propagating effects heretofore described. Outer sleeve 68 is aluminum and has a double taper similar to that of the inner sleeve except that thetaper is formed along its inside wall surface, such sleeve serving to effect a second delay gradient in the propagation of the lateral detonation front, it having been found that such. outer sleeve results in a margin of improvement in attaining a more nearly perfect simultaneous detonation along the length of bore 72 of the explosive charge '74. As with the other sleeves heretofore discussed, undesirable effects may take place within a. certain radial distance beyond the sleeve, and a buffer zone is necessary thereabout. It is desirable that the space taken up by the outer sleeve and its buffer zone be as small as possible to conserve pay load volume. ,It has been found that such space can be'substantially reduced it instead of making the outer sleeve of the same material as the inner sleeve, it is made of an inert material such as aluminum which has the characteristics of effecting a de-.

lay upon a lateral detonation wave in proportion to its thickness but with the magnitude of suchdelay substantially less than that attainable V inert materials heretofore mentioned. A loosely packed with steel, glass, brass, the

explosive 76 such as tetryl with a density of 1.0 gram per cubic centimeter is disposed between the outside wall surface of outer sleeve 68 and warhead charge 74, such explosive being compressible under the outwardly propagating eitects and therefore serving as a butter zone. Employing such explosive in the otherwise void space also adds a margin of explosive energy to the overall explosive capability of the warhead.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In a warhead having a first explosive material with a cylindrical bore therein co-extensive with its length and an elongated cylindrical initiator disposed within said bore extending between opposite ends thereof, means for detonating said initiator substantially at a point along its length, said initiator being of such a character that when detonated at said point it produces a detonation front which propagates in axial and radial directions, a first tube disposed between the initiator and the wall of the bore surrounding and engaging said initiator and having decreasing wall thickness in a direction away from said point and constructed of a material having the property of delaying the propagation of said detonation front, said first tube and the wall of the bore being radially spaced to protect the first explosive material from damage by outward propagation of shock wave and particles of said first tube which emerge from the first tube ahead of the detonation wave, whereby a detonation front is efiFected in which all parts of the radially propagating portions of the front substantially simultaneously reach the wall of the bore to cause simultaneous initiation of the warhead along its length.

2. A warhead in accordance with claim 1 wherein said means for detonating is adapted to detonate said initiator at one of its ends, said tube tapering in thickness to the other end.

3. A warhead in accordancewith claim 1, wherein said means for detonating is adapted to detonate said initiator at a zone substantially midway the ends of said initiator, said tube decreasing in wall thickness in both directions away from the zone midway its ends.

4. A warhead in accordance with claim 1 including a second tube disposed in the space between the first tube and the wall of the bore and having a decreasing wall thickness in a direction away from the transverse plane including said point of detonation and constructed of apmaterial having the property of delaying the propagation of said detonated front, said first and second tubes being radially spaced to protect the second tube from damage by shock wave and particles of said first tube emerging from the first tube, and said second tube and he wall of the bore being radially spaced to protect the first explosive material from damage by shock wave and'particles of said second tube emerging from the sec ond tube. V

5. A warhead in accordance with claim 4 in which said second tube is constructed of a material which delays the propagation of the detonation front to a lesser degree than the material of said first tube.

6. A warhead in accordance with claim 4, said space between the second tube and the wall of the bore containing a second explosive material constructed of loosely packed material to thereby augment the explosive force of the first explosive material." a V p 7. A warhead in accordance with claim 1 including a second tube disposed in the space between the first tube.

and the wall of the bore and having a.decreasing wall thickness in a direction away from the. transverse plane.

7 including said point of detonation and constructed of a material having the property of delaying the propagation of said detonation front and to lesser degree of delay than the material of said first tube, said'first and References Cited in the file of this patent UNITED STATES PATENTS Frothingham Mar. 6, 1883 Moses Oct. 15, 1957 Howard et al May 3, 1960 Meddick Apr. 3, 1962 FOREIGN PATENTS Great Britain Aug. 20, 1952 

1. IN A WARHEAD HAVING A FIRST EXPLOSIVE MATERIAL WITH A CYLINDRICAL BORE THEREIN CO-EXTENSIVE WITH ITS LENGTH AND AN ELONGATED CYLINDRICAL INITIATOR DISPOSED WITHIN SAID BORE EXTENDING BETWEEN OPPOSITE ENDS THEREOF, MEANS FOR DETONATING SAID INITIATOR SUBSTANTIALLY AT A POINT ALONG ITS LENGTH, SAID INITIATOR BEING OF SUCH A CHARACTER THAT WHEN DETONATED AT SAID POINT IT PRODUCES A DETONATION FRONT WHICH PROPAGATES IN AXIAL AND RADIAL DIRECTIONS, A FIRST TUBE DISPOSED BETWEEN THE INITIATOR AND THE WALL OF THE BORE SURROUNDING AND ENGAGING SAID INITIATOR AND HAVING DECREASING WALL THICKNESS IN A DIRECTION AWAY FROM SAID POINT AND CONSTRUCTED OF A MATERIAL HAVING THE PROPERTY OF DELAYING THE PROPAGATION OF SAID DETONATION FRONT, 